Topics in ChemistryChemistry Scheme of Work, SS1, First Term Chemistry Scheme of Work, SS1, Second Term Chemistry Scheme of Work, SS1, Third Term Compounds in Chemistry: Characteristics of Compounds Types of Mixture: Homogenous and Heterogeneous Mixtures Mixtures: Characteristics of Mixtures Physical Properties of Matter explained with Examples Chemical Properties of Matter explained with Examples Differences between Physical and Chemical Change Ionic Theory and Electrolysis Physical and Chemical Properties of Acids States of Matter: Characteristics of Solids Liquid State of Matter: Characteristics of Liquids Gaseous State of Matter: Characteristics of Gases Molar Mass, Worked Examples and Differences with Molecular Mass Elements: Characteristics of Elements Salts and Types of Salt in Chemistry Mixtures and Separation of Mixtures Mixtures and Separation of Mixtures - part 2 Mixtures and Separation of Mixtures - part 3
Academic Questions in Chemistry
The Separating Funnel is a technique used in the separation of mixtures. Another name for Separating Funnel is the _____ Funnel.
2NH4+(aq) + Ag+(aq) -> 2H4AgN
The equation above represents _____ acid.
A. Svante Arrhenius'
C. Gilbert Lewis'
E. Sir Isaac Newton's
F. Albert Einstein's
According to Brønsted Thomas Martin Lowry, an acid is defined as _____.
A. Any substance that produces hydrogen ion (H+) when dissolved in water
B. A substance that accepts electron pair in a chemical reaction
C. A substance that gives out hydronium ion (H3O+) when dissolved in water
D. A substance that donates a proton in a chemical reaction
E. A substance that reacts with a base to form salt and water
F. A substance whose hydrogen ions (H+) are displaced after a reaction with metals higher in the activity, reactivity or electrochemical series
Which of the following is NOT a characteristic of chemical change?
Which of the following statement is FALSE concerning a physical change _____.
The following substances will sublime EXCEPT _____.
Which of the following is a state of matter?
The ideal way of separating a mixture of blood is through _____.
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Diffusion involves the movement of gaseous, liquid and solid particles from a region of higher concentration to that of lower concentration.
Consider the analogy below:
When a perfume is sprayed in a room, the particles of the perfume will move from a region of higher concentration (region where the perfume was sprayed) to a region of lower concentration (other regions in the room where the perfume wasn’t sprayed). As a result, anyone present in this region of lower concentration will also perceive the scent of the perfume.
This movement of particles from a region of higher concentration to a region of lower concentration is known as diffusion.
The particles undergoing diffusion can be gaseous, liquid or solid; and the movement of such particles must be from a region of higher concentration to a region of lower concentration
Diffusion is fastest in gaseous particles. This is due to the fact that gaseous particles are able to move freely since the cohesive or binding forces between them are extremely small or negligible.
Note: Diffusion can also occur in liquid and solid particles. It is slowest in solid particles.
Diffusion is technically not the same thing as effusion. Diffusion always accompanies effusion; with both happening almost simultaneously.
Effusion is the movement of gaseous particles through a very small opening; and is always accompained by diffusion.
For instance; when an inflated balloon is pierced with a needle, both effusion and diffusion will occur.
When diffusion occurs, it continues until equilibrium is attained. This will imply that; from our previous instance, the scent of the perfume will continue to move from the region of higher concentration to the region of lower concentration until every part of the room becomes equally filled, (assuming all external openings have been shut).
Note: When a gas has a high rate of diffusion, it will take a shorter time for diffusion to occur in such gas; (that is, it will diffuse rapidly).
Conversely, diffusion will take a longer time for gases with lower rate of diffusion; (that is, such gases will diffuse slowly).
The Scottish chemist Thomas Graham (1805-1869) studied the rate at which gases diffuse. He established a law of diffusion (called Graham’s law of diffusion).
Graham’s law of diffusion states that the rate (r) of diffusion in a gas at a given temperature is inversely proportional to the square root of its density or molecular mass (m).
Below is an equation on Graham's Law of Diffusion.
Also Note that: "The vapour density (v.d) of a gas is equal to half its relative molecular mass(r.m.m).
Therefore: r.m.m. = 2 x v. d
30cm3 of a gas with an empirical formula of CH3 diffuses through a porous partition in 45.2s. If 30 cm3 of hydrogen diffused in 11.7s under the same conditions. Calculate:
(Mass of H2 = 2)
(i) Vapour density of the CH3 gas
Using the formula derived from the above diagram:
tx/tH= √mx /√mH
t = time, m = molar mass, x = CH3 and H = hydrogen
Time taken for CH3 to diffuse = 45.2s
Time taken for H2 to diffuse = 11.7s
Mass of H2 = 2
Mass of CH3 = ?
Let's substitute these values into the above formula:
45.2/11.7 = √(mx/2)
2(45.2/11.7)2 = mx
mx = 2 x 14.92
mx = 29.84g
Mass of CH3 = 29.84g
r.m.m = 2 x v.d
Where r.m.m = Relative Molecular Mass and v.d = Vapour Density
v.d = r.m.m./2
v.d = 29.84/2
v.d = 14.92
(ii) Molecular formula of the gas CH3
xCH3 = 30
15x = 30
x = 2
Therefore, molecular formula = C2H6 which is Ethane
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Amazing facts in Chemistry
The only letters that failed to appear on the periodic table are letters:
Gold and copper are the only two non-silvery colored metals.
Copper is the only metal that is naturally antibacterial. This is why you would see some children utilize 'copper' water bottles in schools
Water actually freezes faster when it’s warm than when it’s cold
Most element in their pure state exists physically in different forms. For instance, pure carbon can exist as both diamond and graphite. This phenomenon is called allotropy.
If you pour a handful of salt into a full glass of water, the water level will go down rather than overflowing the glass.
Similarly, if you mix half liter of water and half litre of alcohol, the total volume of the liquid will be les than one litre
NOTABLE POINTS IN Chemistry